1. Technical Field
The present invention generally relates to a backlight module and a display device thereof. Particularly, the present invention relates to a reflective plate of a backlight module.
2. Description of the Prior Art
Technologies are being developed daily, with the optoelectronics industry continuously researching and developing greener and brighter lighting sources. For instance, light-emitting diodes (LED), which have advantages of saving energy while producing little heat, have become the common lighting source by replacing conventional lighting devices. LEDs are also being applied to various fields, such as flash lights, lamps, display devices, advertisement boards, as well as the outer walls of buildings. From this, it can be seen that LEDs are deeply entrenched in modern life. For example, liquid crystal displays utilizing backlights with LEDs have gradually become indispensible electronic products in households as they not only greatly cut down on the power usage rates, but also maintain excellent picture quality.
Referring to FIG. 1A, FIG. 1A illustrates a side-view of a conventional liquid crystal display (LCD) employing a backlight module with direct lighting. Typically, conventional backlight modules include an optical film 1A, a diffuser plate 1B, a plurality of light sources 1D where each light source 1D has a lens 1C, and a reflective plate 1E, wherein the light source 1D is a LED disposed on the reflective plate 1E. The optical film 1A and the diffuser plate 1B can increase light smoothness as well as improve optical performance. In practice, light originating from the light source 1D will travel in the direction of the arrow in FIG. 1 towards the diffuser plate 1B due to the shape of the lens 1C.
However, there are still many deficiencies with conventional displays using LEDs as light sources. Referring to both FIGS. 1A and 1B, FIG. 1B illustrates a top view of the conventional backlight module. As shown in FIGS. 1A and 1B, the light sources 1D is organized on the reflective plate 1E in a grid-like manner, surrounding the center areas 1F. In practice, due to the fact that the lens 1C increases the light-emitting angle (ie. range of degree at which light is emitted) of the light source 1D such that light may be emitted towards the side directions, light from the light source 1D will overlap with light from adjacent light sources 1D. The overlapping light over each will cause each center area 1F to produce bright spots. In cases of slim/thin backlight modules wherein the space between the diffuser plate 1B and the light sources 1D is decreased, this bright spot phenomenon is even more pronounced.
In order to overcome the bright spot problem, manufacturers have resorted to increasing the number of light sources 1D to increase the light density. However, although this method shrinks the space between light sources 1D, the material cost as well as the overall weight of the product has also correspondingly increased as a consequence. As modern displays continually trend toward larger dimensions, a solution is necessary to solve the increased material cost and product weight problem. Furthermore, some manufacturers have also resorted to trying to reengineer the diffuser plate 1B through ink printing methods to improve the light smoothness. However, larger dimension displays (e.g. displays with dimensions greater than 71 inch) are not able to utilize diffuser plates 1B formed through ink printing methods. As such, this method still does not overcome the mentioned bright spots problem.
In other words, although LEDs are bright and stable sources of light, the underlying problem of light generated from LEDs being uneven over the entire display needs to be improved in order to increase the display quality.